Rails Step By Step “Guide”

Start a new rails project:

Reference: https://github.com/turingschool-examples/task_manager_rails

This will start a new Rails App with postgresql as database and skip the usage of Spring and Turbolinks (method used in task_manager):

rails new task_manager -T -d="postgresql" --skip-spring --skip-turbolinks

Useful testing gems to be added to Gemfile:

group :development, :test do
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
  gem 'rspec-rails'
  gem 'capybara'
  gem 'launchy'
  gem 'pry'
  gem 'simplecov'
  gem 'shoulda-matchers'
  gem 'orderly'
end

Run bundle and update:

bundle install
bundle update

Add rspec (this will create the spec directory, rails_helper.rb, and spec_helper.rb)

rails g rspec:install

Create app’s database:

rails db:create

If using Shoulda, ensure this is at the bottom of the rails_helper.rb file (within the existing end block)

Shoulda::Matchers.configure do |config|
    config.integrate do |with|
      with.test_framework :rspec

      with.library :rails
    end
  end

If using Simplecov, ensure this is at the very top of the rails_helper.rb file

require 'simplecov'
SimpleCov.start

Preferred table creation which adds model and spec directories and files:

rails generate model Table name:string otherfield:string otherfield:string

(make sure to run rails db:migrate after adding a table)

(manually) Add a table with attributes to database (3 separate examples) reference :

rails generate migration CreateArtist title:string genre:string
rails generate migration CreateSong name:string
rails g migration CreatePlaylists name:string

(make sure to run rails db:migrate after adding a table)

Add a column to an existing table:

rails generate migration add_age_to_artists age:string

Remove a column from an existing table:

rails generate migration remove_column :table_name, :column_name

Add default value to pending migration (this is done in the migration file prior to running db:migrate by including default: <default value>:

class AddAgeToArtists < ActiveRecord::Migration
  def change
    add_column :artists, :age, :string, default: 33
  end
end

Create a one-to-many relationship with existing tables (having created artist and song above, we can add Artists to Songs):

rails g migration AddArtistsToSongs artist:references

Create a many-to-many relationship with existing tables via join table:

rails g migration CreatePlaylistSongs song:references playlist:references

Different ways to associate resources to one another (this example is for a one-to-many relationship (Artist has many songs):

artist = Artist.create(name: 'Prince')
song = Song.create(title: 'Raspberry Beret', length: 345, play_count: 34, artist: artist)

OR:

artist = Artist.create(name: 'Prince')
song = Song.create(title: 'Raspberry Beret', length: 345, play_count: 34, artist_id: artist.id)

OR:

artist = Artist.create(name: 'Prince')
song = artist.songs.create(title: 'Raspberry Beret', length: 345, play_count: 34)

Example of relationships syntax in models (in this case a many to many relationship between songs and playlists:

Join Table (PlaylistSongs:

#app/models/playlist_song.rb
class PlaylistSong < ApplicationRecord
  belongs_to :playlist
  belongs_to :song
end

PlaylistSongs Test: # spec/models/playlist_song_spec.rb

require 'rails_helper'

RSpec.describe PlaylistSong, type: :model do
  describe "relationships" do
    it {should belong_to :playlist}
    it {should belong_to :song}
  end
end

Playlist Model:

#app/models/playlist.rb

class Playlist < ApplicationRecord
  has_many :playlist_songs
  has_many :songs, through: :playlist_songs
end

Playlist Spec Test:

# spec/models/playlist_spec.rb

require "rails_helper"

RSpec.describe Playlist, type: :model do
  describe "relationships" do
    it { should have_many :playlist_songs}
    it {should have_many(:songs).through(:playlist_songs)}
  end
end

Song Model

#app/models/song.rb

class Song < ApplicationRecord
  belongs_to :artist
  has_many :playlist_songs
  has_many :playlists, through: :playlist_songs
end

Song Spec Test:

#spec/models/song_spec.rb

require 'rails_helper'

RSpec.describe Song do
  describe 'relationships' do
    it {should belong_to :artist}
    it {should have_many :playlist_songs}
    it {should have_many(:playlists).through(:playlist_songs)}
  end

Example of model testing for attributes without validations:

describe 'Attributes' do
  it {should allow_value('Tim Robbins').for(:name) }
end